Stainless Nuts, Bolts and Washers
Good stainless hardware is essential for any home-brew antenna builder. Stainless Steel normally comes in two popular guises, although there are more specialist metals as well. First on the table is 304 stainless which is commonly called ‘A2‘. This is probably the most common type of stainless steel on offer. The chances are, if you buy ‘off-the-shelf’ stainless, it will be A2.
The other is called 316 or ‘A4‘. This is a notch up from A2 being that it’s designed to withstand the harsh punishment of sea water. A4 is commonly called ‘Marine Grade Stainless‘ as it performs exceptionally well in salt water environments such as hardware used in boat and ship construction. It’s also slightly stronger than A2. Cost wise, it’s about 20% more expensive than A2. Saying that, for 99% of constructors – A2 will do a fine job for everyday use. If you live next to the sea, then A4 may be worth the extra outlay and consideration.
For the tech boffins amongst you – there’s more here
Jubilee Clips or Worm Drives?
Coupled with the normal ‘nuts and bolts’ are clamps which retain the element tubes. The ‘Jubilee‘ style hose clip has been around forever [or it seems the case], however I found the Jubilee clip was somewhat limited when used repeatedly and the tightening torque lower than more modern ‘worm-drive’ alternatives. At Vortex I settled for the ‘Tridon‘ stainless worm drive clamps from the USA. The worm-drives seem better suited especially when tightened and loosened frequently [in tuning for example] and additionally, the lower/higher opening range covered by each Jubilee clamp was extremely limited. The Tridons covered a much wider span.
For element tubes we recommend the ‘620 Series‘ Tridons. The 620-006 stainless worm-drive will fit tubes from 9 to 22mm diameter which is great for smaller and medium sized diameter tubes with just one size clamp. Equally, the 620-012 clamp covers diameters from 14-32mm. So with two clamps you can cover a really wide range of tubes with plenty of overlap.
For UK buyers is that we have a supplier of Tridon on our doorstep in Zero Clips [Birmingham].
The Tridon range are not that expensive and I found that buying say 100 Tridon 620-006 units was not overly expensive at £25.00 for 100 clamps [that works out at 25p each]. Checking eBay today, the price [generally] for 10 stainless Jubilee clamps which only covered a 13 to 20mm range worked out at £14.00. There’s really no contest. Go the ‘Tridon’ route.
And finally, the chances are that somewhere during your construction journey you’ll also need some ‘P’ Clips. These clips are manufactured by Mikalor [Spain] and are A4 [Marine Grade] stainless and generally used for clamping hairpin rods to shorting bars and the same rods to element tubes. We also used them for gamma match shorting bar clips. A trusted supplier in the the UK is JML Henderson who is happy to supply you pretty much any quantity.
Here’s a rundown of the required ‘P’ clip size and what diameter rods/tubes they fit.
The clips shown in the list below fit ‘snug to tight‘ so allow for some expansion during tightening.
Remember to strip the rubber lining off 🙂
Size 5 – Fits hairpin rods of 5/16ths of an inch
Size 5 – Fits gamma rods of 5/16ths of an inch
Size 9 – Fits tubes of 12mm or 1/2 inch diameter
Size 12 – Fits tubes of 16mm or 5/8 inch diameter
Size 16 – Fits tubes of 20mm or 3/4 inch diameter
Size 20 – Fits tubes of 25mm or 1 inch diameter
Size 26 – Fits tubes of 30mm or 1 1/4 inch diameter
‘TIP’ – Follow this guide to avoid making your clamps twisted, flattened and poor fitting!!
When fitting the ‘P’ clamp, open up slightly by bending the top of the clamp upwards and remove the rubber lining. Fit the clamp loosely over the rod/tube. Bend the top of the clamp downwards over the tube/rod.
DO NOT BEND THE BASE OF THE CLAMP UPWARDS – IT WILL RENDER THE CLAMP USELESS
Follow the above info and it will fit nicely as you’ve used the rod/tube as a former.
Packs of 10 are available here. Check out the JML Henderson eBay store or direct online here.